Get Reactive With Project Reactor and Spring 5

Transcript

259 slides

Get Reactive With Spring 5 And Project Reactor by Oleh
Dokuka
• JSE at Levi9 • 6+ dev experience • Spring
fan • Reactivity preacher /oleh.dokuka /OlegDokuka /OlehDokuka WHO AM I?
Agenda 1. Why Reactive? 2. Reactivity Generations 3. Reactive Streams
4. Project Reactor 5. Reactivity in Action (Project Reactor + Spring 5)
So, why Reactive?1
Requirements of Nowadays https://sites.psu.edu/luopassion2/2016/01/25/a-brief-history-of-the-internet-of-things-iot/
Lean resource management https://i.ytimg.com/vi/EiH1sJCDs9c/maxresdefault.jpg
Asynchrony http://www.cntraveler.com/story/the-main-reasons-your-passport-application-will-be-denied
Fault Tolerance
Powerful way of thinking http://www.wallpaperup.com/200710/pipes_cranes.html
Reactive-Manifesto2
Sounds Cool
Reactivity Generations 3
Handler Observer Java
Skill Knowledge Rx.NET
Akka RxJava
RxJava AkkaStreams
RxJava 2 AkkaStream Project Reactor Reactive Streams Speciﬁed
None
Reactive Streams4
What is the Purpose?
Backpressure
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Common API
Publisher Subscriber
Publisher Subscriber public interface Publisher<T> { public void subscribe( Subscriber<?
super T> s ); }
Publisher Subscriber public interface Subscriber<T> { public void onSubscribe(Subscription s);
public void onNext(T t); public void onError(Throwable t); public void onComplete(); }
Publisher Subscriber Subscription
Publisher Subscriber Subscription public interface Subscription { public void request(long
n); public void cancel(); }
Publisher Subscriber Subscription public interface Subscription { public void request(long
n); public void cancel(); }
Publisher Subscriber Subscription
Processor Publisher Subscriber Subscription
Publisher Subscriber Subscription Processor public interface Processor<T, R> extends Subscriber<T>,
Publisher<R> {}
Example
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Project Reactor
by
RxJava-like API
Reactive Types
Flux
like Stream<T>
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Mono
like CompletableFuture<T>
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Useful Operators
Operator == Very Smart Publisher
merge .merge(…)
zip .zip(…)
zip .zip(…)
publish .publish(…)
.materialize(…) materialize
materialize .materialize(…)
Thread A Thread Main .publishOn(…) publishOn
None
RxJava.observeOn == Reactor.publishOn
Remember!
Nothing happens until .subscribe ()
Reactivity in Action
What we`re going to do?
Refactoring
What do we have?
Chat Application
Functionality • Gitter Chat Communication • Messaging Statistic
Demo
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Toolkit • Spring Framework 4 • Spring Boot • Spring
MVC • Spring Data JPA
Architecture
User Client Gitter Service Whole Application DB Layer Service Layer
Controllers Layer
Controllers Layer
Returns Thymeleaf View
REST Resources
Services Layer
External Chats SPI
Domain Services
Gitter integration
Implementation
Persistence Layer
Database Model
How it works?
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Problems
Problems • Pulling model
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Problems • Pulling model • Too much blocking I/O
Solutions
Apply Reactive Manifesto
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Async Messaging Push Model
Apply Streaming API
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Async Messaging Elasticity
Dedicate ThreadPool
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Async Messaging Push Model
Apply WebSocket
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How to bring it all together?
Spring 5
Painless replacement
WebFlux @Controller, @RequestMapping,… Spring MVC Servlet API Servlet Container Spring
Web Reactive Reactive HTTP Servlet, Netty, Undertow
None
None
@RestController @RequestMapping("/api/v1/statistics") public class StatisticResource { private final StatisticService statisticService;
@Autowired public StatisticResource( StatisticService statisticService) { this.statisticService = statisticService; } @GetMapping("/users") public List<UsersStatisticVM> getUsersStatistic() { return statisticService.getUsersStatistic(); } }
@Autowired public StatisticResource( StatisticService statisticService) { this.statisticService = statisticService; } @GetMapping("/users") public List<UsersStatisticVM> getUsersStatistic() { return statisticService.getUsersStatistic(); } }
@Autowired public StatisticResource( StatisticService statisticService) { this.statisticService = statisticService; } @GetMapping("/users") public Flux<UsersStatisticVM> getUsersStatistic() { return Flux.fromIterable(statisticService .getUsersStatistic()); }
@Autowired public StatisticResource( StatisticService statisticService) { this.statisticService = statisticService; } @GetMapping("/users") public Flux<UsersStatisticVM> getUsersStatistic() { return Flux.fromIterable(statisticService .getUsersStatistic()); }
Project Reactor + Netty Integration
Why Netty?
Non-Blocking,Reactive Server
Reactive Architecture
Data Base Connection Pipe Gitter Connection Pipe
Refactoring Structure
1. Blocking I/O Refactoring 2. Service Refactoring 3. Endpoints Refactoring
4. Pipeline Testing
None
Blocking I/O Refactoring
None
Reactive DB Access via ReactiveCrudRepository<T, ID>
interface ReactiveCrudRepository<T, ID> extends Repository<T, ID> <S extends T> Mono<S>
save(S entity); <S extends T> Flux<S> saveAll(Iterable<S> entities); <S extends T> Flux<S> saveAll(Publisher<S> entityStream); Mono<T> findById(ID id); Mono<T> findById(Mono<ID> id); Mono<Boolean> existsById(ID id); Mono<Boolean> existsById(Mono<ID> id); Flux<T> findAll(); Flux<T> findAllById(Iterable<ID> ids); Flux<T> findAllById(Publisher<ID> idStream); Mono<Long> count(); Mono<Void> deleteById(ID id); Mono<Void> delete(T entity); Mono<Void> deleteAll(Iterable<? extends T> entities); Mono<Void> deleteAll(Publisher<? extends T> entityStream); Mono<Void> deleteAll(); }
interface ReactiveCrudRepository<T, ID> extends Repository<T, ID> <S extends T> Mono<S>
save(S entity); <S extends T> Flux<S> saveAll(Iterable<S> entities); <S extends T> Flux<S> saveAll(Publisher<S> entityStream); Mono<T> findById(ID id); Mono<T> findById(Mono<ID> id); Mono<Boolean> existsById(ID id); Mono<Boolean> existsById(Mono<ID> id); Flux<T> findAll(); Flux<T> findAllById(Iterable<ID> ids); Flux<T> findAllById(Publisher<ID> idStream); Mono<Long> count(); Mono<Void> deleteById(ID id); Mono<Void> delete(T entity); Mono<Void> deleteAll(Iterable<? extends T> entities); Mono<Void> deleteAll(Publisher<? extends T> entityStream); Mono<Void> deleteAll(); }
Code session
.publishOn() public static <S, V> Mono<V> mono( Mono<S> input, Function<...>
transformer ) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); }
public static <S, V> Mono<V> mono( Mono<S> input, Function<...> transformer
) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); } .publishOn()
) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); } .subscribeOn() MonoProcessor
) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); } .subscribeOn() MonoProcessor
) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); } MonoProcessor .subscribeOn() …subscribe();
) { MonoProcessor<V> monoProcessor = MonoProcessor.create(); input .publishOn(Schedulers.elastic()) .transform(transformer) .subscribe(monoProcessor); return monoProcessor .subscribeOn(Schedulers.elastic()); } …subscribe(); MonoProcessor .subscribeOn() …subscribe();
Service Refactoring
Gitter Service
Reactive WebClient out of the box
public interface WebClient { UriSpec<RequestHeadersSpec<?>> get(); //omitted... static WebClient create()
{ return new DefaultWebClientBuilder().build(); } interface RequestHeadersSpec<S extends RequestHeadersSpec<S>> { //omitted... Mono<ClientResponse> exchange(); //omitted... } interface ResponseSpec { <T> Mono<T> bodyToMono(Class<T> bodyType); <T> Flux<T> bodyToFlux(Class<T> elementType); <T> Mono<ResponseEntity<T>> toEntity(Class<T> bodyType); <T> Mono<ResponseEntity<List<T>>> toEntityList(Class<T> element } }
public interface WebClient { UriSpec<RequestHeadersSpec<?>> get(); //omitted... static WebClient create()
{ return new DefaultWebClientBuilder().build(); } interface RequestHeadersSpec<S extends RequestHeadersSpec<S>> { //omitted... Mono<ClientResponse> exchange(); //omitted... } interface ResponseSpec { <T> Mono<T> bodyToMono(Class<T> bodyType); <T> Flux<T> bodyToFlux(Class<T> elementType); <T> Mono<ResponseEntity<T>> toEntity(Class<T> bodyType); <T> Mono<ResponseEntity<List<T>>> toEntityList(Class<T> element } }
None
Code Session
@Autowired public GitterService( GitterClient gitterClient ) { gitterMessageSource = Flux.from(
gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); }
gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); } .onBP()
gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); } .onBP()
.onBP() @Autowired public GitterService( GitterClient gitterClient ) { gitterMessageSource =
Flux.from( gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); }
Flux.from( gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); } …subscribe();
Flux.from( gitterClient .getMessages(null) ) .onBackpressureBuffer() .publish(1) .autoConnect(0); } …subscribe(); …subscribe();
Message Service
None
Code Session
@Override public Flux<MessageVM> latest() { return chatClient.stream() .transform(MessageMapper ::toViewModelUnits );
} @Override public Flux<MessageVM> latest() { return chatClient.stream() .transform(MessageMapper ::toViewModelUnits ); } @Override public Flux<MessageVM> latest() { return chatClient.stream() .transform(MessageMapper ::toViewModelUnits ); } .transform()
Statistics Service
None
Code Session
@Autowired public DefaultMessageService( MessageRepository messageRepository, ChatService<MessageResponse> chatClient, MessageBroker messageBroker )
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); }
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } .transform()
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } Channel .materialize()
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } .materialize() .transform()
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } .transform() .materialize()
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } Channel .materialize()
Channel @Autowired public DefaultMessageService( MessageRepository messageRepository, ChatService<MessageResponse> chatClient, MessageBroker messageBroker
) { this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } .materialize()
{ this.chatClient = chatClient; Flux<Message> saved = messageRepository .saveAll(chatClient.stream() .transform(MessageMapper::toDomainUnits) ); messageBroker.createChannel( "statisticChanged", saved.materialize() ); } .materialize() Channel
Code Session
this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize()
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .retry() Channel
.retry() Channel this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof
USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1);
.retry() Channel this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .retry() Channel .dematerialize()
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); Channel .retry() .dematerialize()
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .flatMap() .cache(1) .mergeWith .defer(statistic)
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .flatMap() .cache(1) .mergeWith .defer(statistic) …subscribe();
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .flatMap() .cache(1) .mergeWith .defer(statistic) …subscribe();
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .flatMap() .cache(1) …subscribe(); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .mergeWith .defer(statistic)
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .flatMap() .cache(1) …subscribe();
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); …subscribe(); .flatMap() .cache(1)
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); Channel .retry() .dematerialize()
.flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1); .retry() .dematerialize() .flatMap()
.retry() .dematerialize() .flatMap() this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err
instanceof USE) .dematerialize() .flatMap(s -> doGetUserStatistic()) .mergeWith(Mono .defer(this::doGetUserStatistic) ) .cache(1);
.dematerialize() .flatMap() .cache(1) this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err
.dematerialize() .flatMap() .cache(1) this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err
.flatMap() .cache(1) this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof
.flatMap() .cache(1) this.statisticPublisher = messageBroker .channel("statisticChanged") .retry(err -> err instanceof
Code Session
private Mono<UsersStatisticVM> doGetUserStatistic Flux<UserVM> topActiveUser = userRepository .findAllOrderedByActivityDesc(PageRequest.o .map(UserMapper::toViewModelUnits); Flux<UserVM>
topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } .map(…) .defaultIfEmpty(…) .zip(…)
topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } .defaultIfEmpty(…) .zip(…) .fromDirect(…)
topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } .map(…) .defaultIfEmpty(…) .zip(…) null
topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } .map(…) .defaultIfEmpty(…) .zip(…) null null
topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } private Mono<UsersStatisticVM> doGetUserStatistic Flux<UserVM> topActiveUser = userRepository .findAllOrderedByActivityDesc(PageRequest.o .map(UserMapper::toViewModelUnits); Flux<UserVM> topMentionedUser = userRepository .findAllOrderedByMentionDesc(PageRequest.of .map(UserMapper::toViewModelUnits); return Mono.fromDirect( Flux.zip( topActiveUser.defaultIfEmpty(EMPTY_USER), topMentionedUser.defaultIfEmpty(EMPTY_USER) UsersStatisticVM::new ) ); } .defaultIfEmpty(…) .zip(…) .fromDirect(…)
Endpoints Refactoring
None
Reactive WS out of the box
public interface WebSocketSession { String getId(); HandshakeInfo getHandshakeInfo(); DataBufferFactory bufferFactory();
Flux<WebSocketMessage> receive(); Mono<Void> send(Publisher<WebSocketMessage> messages); default Mono<Void> close() { return close(CloseStatus.NORMAL); } Mono<Void> close(CloseStatus status); WebSocketMessage textMessage(String payload); WebSocketMessage binaryMessage( Function<DataBufferFactory, DataBuffer> payloadFactory); WebSocketMessage pingMessage( Function<DataBufferFactory, DataBuffer> payloadFactory); WebSocketMessage pongMessage( Function<DataBufferFactory, DataBuffer> payloadFactory); }
Code session
@Override public Publisher<?> handle( Publisher<Object> in ) { return Flux.merge(
messageService.latest(), statisticService .usersStatisticStream() ); } network .merge()
.merge() @Override public Publisher<?> handle( Publisher<Object> in ) { return
Flux.merge( messageService.latest(), statisticService .usersStatisticStream() ); } network
network .merge() @Override public Publisher<?> handle( Publisher<Object> in ) {
return Flux.merge( messageService.latest(), statisticService .usersStatisticStream() ); }
network .merge() @Override public Publisher<?> handle( Publisher<Object> in ) {
return Flux.merge( messageService.latest(), statisticService .usersStatisticStream() ); }
Pipeline Testing
StepVerifier
StepVerifier .create(myPublisher) .expectNext(“x”, “y”) .expectComplete() .verify();
Code session
Demo
None
Checkpoints • Message Driven • Resilient • Responsive • Elastic
SUMMARY
Q&A
Resources 1. Why Reactive? [http://www.oreilly.com/programming/ free/why-reactive.csp] 2. Operator Fusion Part
1 [http://akarnokd.blogspot.com/ 2016/03/operator-fusion-part-1.html] 3. Reactive Streams Speciﬁcation [http://www.reactive- streams.org/] 4. Learn Project Reactor [http://projectreactor.io/learn]
Thank you!